Sample preparation for operation and failure analysis is an important tool in providing a detailed inspection of the physical characteristics of a recording head fabricated on a substrate. With the structure of recording heads decreasing in size and becoming more complex, electron microscopy (e.g., scanning electron microscopy) has emerged as a critical tool for highly site-specific operation and failure analysis. More particularly, an important issue is the measurement of critical parameters on a main pole of the recording head. However, the difficulties associated with exposing the main pole of the recording head using conventional techniques make measurement of these critical dimensions inaccurate.
Physical characteristics of the main pole provide critical factors in determining the overall performance of the recording head. These physical characteristics are directly linked to the properties related to electrical and magnetic conductivity of the recording head. The most critical factors for the main pole properties include the flare point and flare angle.
Preparation of the sample structure for use in electron microscopy is necessary for examining the critical dimensions of the recording head. Conventional sample preparation techniques for the sample structure including the recording head include mechanical sectioning (e.g., mechanical lapping techniques). However, since the main pole target on the recording heads is at least one order of magnitude smaller than the thickness removed through any mechanical sectioning technique employed, it is very difficult to hit the main pole target. For instance, the mechanical lapping of the sample may remove too much of the insulator surrounding the main pole thereby damaging the main pole and rendering the sample useless for examination using electron microscopy. On the other hand, the mechanical lapping of the sample may not remove enough the insulator surrounding the main pole. In this case, the main pole has not been exposed enough for use in electron microscopy. As a result, the success rate for exposing the main pole sufficiently for use in electron microscopy is very low.
Another conventional technique used for sample preparation in electron microscopy is to combine the techniques of mechanical sectioning (e.g., mechanical lapping) with focused ion beam (FIB). For example, many FIB steps are used in conjunction with mechanical lapping to fine tune the exposure of the main pole of the recording head for examination in electron microscopy. However, this combined technique is very labor intensive and expensive, both in terms of human and equipment costs when used for failure analysis. As a result, the expense for sample preparation through a combined mechanical sectioning and FIB is cost prohibitive, especially if more than one sample in a batch of recording heads is to be examined. Additionally, because of the time and cost involved, the combined techniques of mechanical sectioning and FIB is not scalable to examine multiple recording heads in a batch of recording heads.
Thus, a need exists for a preparation technique that provides better main pole exposure for operation and failure analysis.